As an electronic expansion valve, there is known an electronic expansion valve with high controllability that regulates the extent of expansion of a refrigerant by changing the extent to which an expansion path is opened using a stepping motor (for example, refer to Patent Document 1), but using a stepping motor is expensive. In response to this, there is known a low priced pulse drive type expansion valve that regulates the extent of expansion of a refrigerant by opening and closing an electromagnetic valve (for example, refer to Patent Document 2).
With the pulse drive type expansion valve (a refrigerant flow rate control device), by on/off controlling the electromagnetic valve, a degree of superheat of an evaporator outlet refrigerant is adjusted to reach a predetermined value, so that operating highly efficiently a refrigerant cycle is possible. An operating configuration of the pulse drive type expansion valve is such that a valve body is opened by a solenoid, and the valve body is closed by a coil spring.